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Identification of Faults and Fractures |
Norsk Hydro Exploration and Production, P.O. Box 200, N-1321 Stabekk, Norway
Dipmeter interpretation has been carried out on seven wells from the Gullfaks Field. Orientation and style of major and associated minor faults have been investigated using dipmeter results. Major faults, as inferred from dipmeter data, are in fairly good agreement with faults defined from seismic interpretation. Several less significant dipmeter-defined faults were below the resolution of seismic data. The orientation of these faults probably corresponds with that expected of antithetic and synthetic faults associated with the main fault system. Analyses of dipmeter results indicate little or no influence of synsedimentary tectonism. Thickness variations of the different formations can be explained by post-depositional faulting (fault cut-out) and erosion. The differences in structural dip between the seven wells support the interpretation that they are located on separate fault blocks. The density of detected faults, one per 140 m (from dipmeter results), proves the presence of an intensely faulted area. This study therefore emphasises the importance of using dipmeter results as a supplement to seismic for the purpose of structural interpretation.
